REACTION OF TRIMETHYLSILYL ENOL ETHERS WITH ISOQUINOLINIUM SALTS. A FACILE SYNTHESIS OF ETHYL 1-(2-OXOALKYL)-1,2-DIHYDROISOQUINOLINE-2-CARBOXYLATES AND THEIR CYCLIZATION
作者:Makoto Wada、Masayuki Nakatani、Kin-ya Akiba
DOI:10.1246/cl.1983.39
日期:1983.1.5
An efficient method is described for the synthesis of ethyl 1-(2-oxoalkyl)-1,2-dihydroisoquinoline-2-carboxylates by C–C bond formation between 2-ethoxycarbonylisoquinolinium chloride and trimethylsilylenolethers. The products were treated with a few bases to afford the corresponding pyrido [2,1-a] isoquinoline derivatives.
Ketones undergo a smooth addition to N-acylisoquinolinium ions in N-methyl-2-pyrrolidinone, under mild conditions, to produce 1-alkylated isoquinoline derivatives in excellent yields with high regioselectivity. The use of commercially available N-methyl-2-pyrrolidinone makes this process quite simple, more convenient and practical.
Addition of trimethylsilyl enol ethers to isoquinolinium salts: a facile synthesis of 1-(2-oxoalkyl)-2-(ethoxycarbonyl)(or acetyl)-1,2-dihydroisoquinolines and their cyclization for the synthesis of isoquinoline alkaloid skeleton